In the various fields such as a manufacture of semiconductor device such like an LSI, a preparation of a flat panel display (FPD) such like a liquid crystal display (LCD) panel, a manufacture of a circuit substrate such like a thermal head and so on, photolithography technology has so far been employed for forming microelements or for conducting fine processing. In the photolithography technology, a positive or negative-working photosensitive resin composition (photoresist) is used to form a resist pattern. These positive or negative-working photoresists are applied on a substrate, mask-adjusted, exposed to light and developed to form a resist pattern. The thus-formed resist patterns are put to use as an etching resist and a resist applied upon impurity ion implantation in manufacturing of, for example, a semiconductor device, an FPD and a circuit substrate or as a plating resist and so on in manufacturing of a magnetic head, and so on.
In these years, as a semiconductor device is becoming highly integrated, wiring required in production process and an element separation width thereof are fined more and more. In order to respond to the situation, a various kind of trials have been being made such as conducting a micronization of resist pattern by utilizing a light with a shorter wavelength, forming a finer resist pattern using a phase shift reticle and so on, development of a new resist to meet these requirements, a development of a novel process, etc. However there are problems that it is difficult to form a fine pattern exceeding a limit of wavelength of light-exposure wavelength by the lithography technology utilizing exposure light so far applied and on the other hand, the price of a device for a short wavelength or a device applying a phase shift reticle etc is high. As one of the methods to solve those problems, a following fine pattern forming method has been proposed wherein a positive or negative-working photoresist so far publicly known is used as a photoresist. That is, after forming a resist pattern by the pattern forming method so far publicly known, an acid-crosslinkable material layer for forming a coated layer is formed on the thus-formed resist pattern. The material layer is then crosslinked and hardened utilizing diffusion of an acid from the resist pattern by heating to be made insoluble in a developer. Thereafter the resist pattern is thickened by removing unhardened area by development to conduct a fining of the resist pattern by narrowing a width between a resist pattern and a neighboring other resist pattern, and as a result a fine resist pattern below a limit resolution of light-exposure wavelength is formed practically and effectively (Following Patent Literature 1, Patent Literature 2 and Patent Literature 3 are to be referred, for example.).
[Patent Literature 1]
    Japanese Laid-Open Patent Publication No. Hei 5-241,348[Patent Literature 2]    Japanese Laid-Open Patent Publication No. Hei 6-250,379[Patent Literature 3]    Japanese Laid-Open Patent Publication No. Hei 10-73,927
The above-described method is being paid attention to be a useful method as it is not necessary to invest a high price facility such as light-exposure device for a short wavelength and is possible to cut down a dimension of a space area in a resist pattern practically and effectively.
The above-described fine resist pattern forming method so far proposed, wherein a fine resist pattern below a limit resolution of light-exposure wavelength is formed practically and effectively by thickening a resist pattern and narrowing thereby a width between a resist pattern and the other resist pattern, is mainly directed to a resist pattern formed by a KrF resist (KrF responsive radiation sensitive resin composition) and it exhibited the effect towards a KrF resist. Whereas an ArF excimer laser exposure process is proposed in these days aiming at further fining and an ArF resist (ArF responsive radiation sensitive resin composition) is being proposed with it. The KrF resist so far known is required to be transparent to 248 nm light source, whereas the ArF resist is required to be transparent to 193 nm light source. As a result, a polymer having a structure such that a protecting group is introduced into acrylic resin, methacrylic resin or the like is becoming a leading material naturally as the ArF resist. As these protecting groups, an alicyclic protecting group has been proposed, and a hydrophobic property of the polymer itself is getting higher by the introduction of the alicyclic protecting group. On the other hand, a composition for forming a coated layer is a composition comprising a water-soluble resin and water as main components in order not to dissolve a resist pattern film which constitutes the first layer. However a water-soluble resin composition for forming a coated layer so far proposed is not regarded to have a good applying property on a resist pattern of high water repellency such an ArF resist described before. Because of this it is not possible to form a good coated layer. In addition there is a problem that a crosslinked hardened layer having sufficient film thickness is not formed in a coated layer, which is thought to be brought by insufficient acid diffusion from a resist pattern. Besides depending on the kind of polymer contained in an ArF resist, a resist pattern dimension is fluctuated by an electron beam exposure according to a size measuring SEM after forming a resist pattern. Therefore there exists a resist of which it is not possible to conduct an accurate size measurement and it is one of the factors which make a semiconductor manufacturing process difficult.
The present invention was made considering the above described situation. An object of the present invention is to propose a pattern forming method of reducing a separation size or a hole aperture size of a resist pattern below a limit resolution practically and effectively and in a high dimensional controllability, wherein a coated layer is applied on the resist pattern such as an ArF resist pattern which is formed by a way so far applied and has a relatively high water repellency and then modified by heating to form a modified layer which is insoluble in a developer on the surface of the resist pattern and thicken thereby the resist pattern.
Another objects of the present invention are to propose a method of reducing a dimensional fluctuation of the resist pattern caused by an electron beam exposure after a pattern formation, wherein a coated layer is given on a resist pattern such as an ArF resist pattern which is formed by a way so far applied and has a relatively high water repellency and then a modified layer which is insoluble in a developer is formed on the surface of the resist pattern by modification of the coated layer by heating; and an inspection method of a resist pattern by which a dimensional fluctuation caused by irradiation of an electron beam is reduced upon above-described inspection of a size measurement for the resist pattern with a size measuring SEM.
Furthermore another object of the present invention is to propose a water-soluble resin composition which is preferably and suitably used for forming the coated layer in the above-described pattern forming method of reducing a separation size or a hole aperture size of the resist pattern practically and effectively below a limit resolution by thickening the resist pattern, the above-described method of reducing a dimensional fluctuation of is reduced.